The invention relates to a dialysis process for purifying the blood by continuous flow of a dialysate and exchange across the peritoneal membrane.
Heretofore, artificial kidney users have relied basically on two processes for purifying the blood. Hemodialysis involves the circulation of blood through a dialysis machine in which an exchange of the toxic metabolites takes place across an artificial membrane outside of the patient's body. This process requires the assistance of trained personnel and subjects the patient to dangers of mechanical malfunction due to the fact that blood vessels are involved.
Peritoneal dialysis involves the infusion of a sterile dialysate into the peritoneal cavity and after absorbing waste metabolites, the dialysate is discarded. The process is then repeated until the level of metabolytes is reduced to a desired level. This method is commonly referred to as the "Batch" method due to the fact that multiple one or two liter bottles or bags of fresh dialysate solution are utilized which require multiple connections to be made to the catheter inserted in the peritoneal cavity during the dialysis process. The multiple connections made during the course of the dialysis has been thought to be a major cause of the high instance of peritonitis.
Continuous ambulatory peritoneal dialysis offers continuous peritoneal dialysis while still allowing the patient some off time. However, the continuous ambulatory peritoneal dialysis must be done in absence of a machine and multiple bottles or bags of dialysis must be infused daily. Thus, multiple infusions per day requires that multiple connections of bags or bottles to the peritoneal catheter be made. The production of bulk sterile dialysis for the peritoneal process has not been shown to be practical for large scale application particularly for home dialysis.
U.S. Pat. No. 4,311,587 seeks to avoid some of the above problems with peritoneal dialysis by providing a sub-micron filter on line with the fresh dialysate to prevent peritoneal contamination. The system is perambulatory and the bag of dialysate is worn by the patient. The bag may be pressurized by numerous methods and is connected only to the inflow side of the filter. The outflow port of the filter is connected on the other side of the filter so that no peritoneal contaminating source is connected directly to the peritoneal cavity. The system is still basically a batch type system in that multiple bottles or bags of dialysate must be connected to the filter even though direct connection to the peritoneal catheter is not required.
U.S. Pat. No. 4,338,190 discloses a system and process which attempts to avoid the batch process method utilized heretofore in peritoneal dialysis wherein a closed loop peritoneal circuit is provided having a selective membrane across which toxic metabolites are exchanged. A solution is passed on the other side of the selective membrane for maintaining the original concentration of sugar and salt in the peritoneal fluid as the toxic metabolites pass the separator membrane. A double peritoneal catheter provides for the inflow and outflow of the peritoneal fluid. However, the peritoneal fluid is constantly recirculated through the peritoneal cavity and the efficiency becomes reduced slightly because of residual toxins which are put back into the peritoneal cavity. The selective membrane is an expensive disposable item which means that the cost of operating the system is high unless the membrane is recleaned. Pumping the peritoneal fluid through the peritoneal cavity is required making it difficult to assure that the patient stays properly distended during the dialysis process. If the peritoneal membrane is not fully distended, it becomes convoluted around the intestines and pockets are formed where the peritoneal fluid can hide. Incomplete circulation then results with decreased efficiency of dialysis. No control is had over the level of the peritoneal fluid in the peritoneal circuit. There is no way of replenishing the peritoneal fluid should the circuit run low on fluid or run dry.
Accordingly, an important object of the present invention is to provide a continuous flow peritoneal dialysis system and method which avoid the inherent problems and dangers of a batch type peritoneal dialysis system.
Still another important object of the present invention is to provide a peritoneal dialysis system having a high rate of dialysate exchange providing increased dialysis efficiency.
Still another important object of the present invention is to provide a peritoneal dialysis system and method having a high rate of dialysate exchange and dialysis efficiency in which the danger of peritoneal infection is minimized.
Still another important object of the present invention is to provide a continuous-flow single-pass peritoneal dialysis system and method in which the pressure and volume of dialysate in the patient's peritoneal membrane is monitored to provide for proper distention of the membrane at all times.